News

Technical requirements for floodlighting

For the convenience of calculation, the illumination value of floodlighting is generally based on the horizontal illumination. However, in many cases, the purpose of floodlighting requires that the target on the vertical plane can be seen clearly. For example, in sports such as golf and archery, horizontal illumination plays almost no role, because the spectator only needs to see the flight of the ball or its target. To this end, only the side facing the spectator needs to be illuminated.

Designers must recognize the importance of vertical illumination and understand the ratio of horizontal and vertical illumination produced by various lighting systems. In general, if the incident angle of light on the surface is less than 45°, the illumination ratio on the plane at right angles to the surface is lower; if it is greater than 45°, the illumination ratio on the vertical surface is higher. However, there are also limiting factors. When the installation height of the lamp is low or the illumination angle of the floodlight is increased, although the vertical illumination can be increased, glare problems will also occur. If the glare is too strong, it is equivalent to wasting light, because the luminous flux at a large angle is difficult to illuminate the included ground, and the addition of glare will further reduce the visual efficiency of the spectator.

For color television or other demanding applications, the illuminance difference should be better than 5:1, but in general, a change of 10:1 is visually acceptable. For ordinary ground lighting, even more than 20:1 is permissible. This 20:1 ratio is particularly necessary in some cases where the illuminance is intentionally reduced. Small changes in illuminance are easier to see on flat, matte, light-colored surfaces, but less obvious on dark, deeply textured or patterned surfaces. For upright objects, or objects moving on the surface, vertical changes in illuminance are not easily perceived.

Although floodlighting requirements are generally expressed in illuminance, in fact the eye often responds to luminance or images with brightness in the field of vision. This is particularly evident in floodlighting of buildings.

PREVIOUS：Happy New Year！ NEXT：In lighting design, it is necessary to consid